The subject matter disclosed herein relates to semiconductor microelectromechanical based sensors (MEMS) that are used to detect small forces or flexures generated from mechanical stress, chemo-mechanical stress, thermal stress, electromagnetic fields, and the like. More particularly, the subject matter disclosed herein relates to a device for sensing pressure and a method of manufacturing the same.
Advances in semiconductor microelectronic based sensors have greatly reduced the size and cost of such sensors. The electrical and mechanical properties of silicon microsensors, as well as silicon micromachining and semiconductor microelectronic technologies, have improved. For example, micromachined silicon pressure sensors, acceleration sensors, flow sensors, humidity sensors, microphones, mechanical oscillators, optical and RF switches and attenuators, microvalves, ink jet print heads, atomic force microscopy tips and the like are used in various applications in medical, aerospace, industrial and automotive markets. The high yield strength, elasticity at room temperature, and hardness properties of silicon make it an ideal base material for resonant structures that are, for example, useful for sensor structures. Even consumer items such as watches, scuba diving equipment, hand-held tire pressure gauges and sleep apnea machines incorporate silicon micromachined sensors.
The demand for silicon sensors in ever expanding fields of use continues to fuel a need for new and different silicon microsensor geometries and configurations optimized for particular environments and applications. The expanding fields of use for microelectromechanical devices in general, and sensors used to measure forces such as pressure in particular, have created a demand for ever smaller devices. Unfortunately, there has been difficulty producing smaller devices that are also highly sensitive to small changes in pressure. Because of the small size of the devices and the thin nature of the geometries used, it is difficult for conventional techniques to maintain the stringent tolerances required, especially during high volume manufacturing. Additionally, limitations in the depth to which structures may be diffused or implanted within such MEMS devices during manufacturing limit the design and operational characteristics of such devices.
It would be advantageous to provide a method for manufacturing highly sensitive pressure sensors that are not only small in size, but which can be effectively produced in high volume. The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.